ad exchange

An online marketplace for advertisers and publishers to buy and sell inventory, often through real-time auctions.

Set up in a Nasdaq-like exchange for the buying and selling of digital advertisements, an ad exchange is a marketplace where publishers and advertisers can find and execute advertising transactions (similar to what happens on a stock exchange).

An ad network also extends to text link ads where participating sites display text ads in exchange for credits which are then converted (using a predetermined exchange rate) into ads to be displayed on other sites.

Historical perspective: As of 2014, the top players in the ad exchange industry included Google's AdX, Yahoo's Right Media, Facebook Exchange, and AppNexus.